Mitosis and Meiosis
“Mitosis is the type of cell division that results in the formation of two daughter cells each with the same number of chromosomes as the parent cell.”
“Meiosis is a type of cell division that results in the formation of four daughter cells each with half the number of chromosomes as the parent cell.”
Let us have a quick glance at mitosis and meiosis, some important similarities and difference between mitosis and meiosis.
Table of Contents
In single-celled organisms, cell reproduction gives rise to the next generation. In multicellular organisms, cell division occurs not just to produce a whole new organism but for growth and replacement of worn-out cells within the organisms.
Cell division is always highly regulated and follows a highly orchestrated series of steps. The term cytokinesis refers to the division of a cell in half, while mitosis and meiosis refer to two different forms of nuclear division.
Mitosis results in two nuclei that are identical to the original nucleus. Meiosis, on the other hand, results in four nuclei that each has ½ the chromosomes of the original cell. In animals, meiosis only occurs in the cells that give rise to the sex cells (gametes), i.e., the egg and the sperm.
Also read: Cell Cycle
Difference Between Mitosis and Meiosis
The important difference between mitosis and meiosis are mentioned below:
|Difference between Mitosis and Meiosis|
|Interphase||Each chromosome replicates. The result is two genetically identical sister chromatids.||Interphase – Chromosomes not yet visible but DNA has been duplicated or replicated.|
|Prophase||Prophase I – crossing-over recombination – Homologous chromosomes (each consists of two sister chromatids) appear together as pairs. Tetrad is the structure that is formed. Segments of chromosomes are exchanged between non-sister chromatids at crossover points known as chiasmata (= crossing-over).||Prophase –Each of the duplicated chromosomes appears as two identical or equal sister chromatids, The mitotic spindle begins to form. Chromosomes condense and thicken.|
|Metaphase||Metaphase I Chromosomes adjust on the metaphase plate. Chromosomes are still intact and arranged as pairs of homologues.||Metaphase -The chromosomes assemble at the equator at the metaphase plate.|
|Anaphase||Anaphase I Sister chromatids stay intact. But homologous chromosomes drift to the opposite or reverse poles.||Anaphase – The spindle fibres begin to contract. This starts to pull the sister chromatids apart. At the end of anaphase, a complete set of daughter chromosomes is found each pole.|
|Mode of Reproduction||Asexual Reproduction.||Sexual Reproduction.|
|Occurs in||Eukaryotic cells.||Diploid cells.|
|Function||General growth and repair, Cell reproduction||Genetic diversity through sexual reproduction.|
|Cytokinesis||Occurs in Telophase.||Occurs in Telophase I and in Telophase II.|
|Karyokinesis||Occurs in Interphase.||Occurs in Interphase I.|
|Discovered by||Walther Flamming.||Oscar Hertwig.|
- Mitosis is a continuum process of cell division which occurs in all types of living cells.
- Mitosis involves four basic phases – prophase, metaphase, anaphase and telophase.
- Mitosis is the process where the division of cell occurs by asexual reproduction.
- The focus in this class is on an understanding of the process and not memorization of phases.
- The only phase name you will need to remember is metaphase.
- In mitosis the nuclear membrane is broken down, spindle fibres (microtubules) attach to the chromatids at the centromere and pull apart the chromatids.
- When the chromatids reach separate ends of the cells, the spindle fibres disintegrate, and a nuclear membrane rebuilds around the chromosomes making two nuclei.
- Each nucleus is identical to the original nucleus as it was in G1.
Also read: Difference between haploid and diploid
- Meiosis is the form of nuclear cell division that results in daughter cells that have one half the chromosome numbers as the original cell.
- In organisms that are diploid, the end result is cells that are haploid. Each daughter cell gets one complete set of chromosomes, i.e., one of each homologous pair of chromosomes.
- In humans, this means the chromosome number is reduced from 46 to 23.
- The only cells that undergo meiosis will become sperm or eggs.
- The joining together of a sperm and egg during fertilization returns the number of the chromosomes to 46.
- Cells that undergo meiosis go through the cell cycle including the S phase so begin the process with chromosomes that consist of two chromatids just as in mitosis.
- Meiosis consists of meiosis I and meiosis II. In meiosis I homologous chromosomes are separated into different nuclei.
- This is the reduction division; chromosome number is cut in half. Meiosis II is very similar to mitosis; chromatids are separated into separate nuclei.
- As in mitosis, it is spindle fibres that “pull” the chromosomes and chromatids apart.
- The end result of meiosis is four cells, each with one complete set of chromosomes instead of two sets of chromosomes.
Also read: Significance of Meiosis
Similarities Between Mitosis and Meiosis
- Both mitosis and meiosis takes place in the cell nuclei which can be observed under a microscope
- Mitosis and meiosis, both involve cell division
- Both the processes occur in the M-phase of the cell cycle. In both cycles, the typical stages are metaphase, anaphase, telophase and prophase
- In both the cycles, synthesis of DNA takes place
- Cells of nervous tissue and the cardiac muscles tissue do not undergo the process of mitosis and meiosis once they are formed. They do not undergo division further.
Also Read: Meiosis I
The difference between Mitosis and Meiosis is quite apparent. They are two very different processes that have two different functions. Meiosis is required for genetic variation and continuity of all living organisms. Mitosis, on the other hand, is focused on the growth and developments of cells. Meiosis also plays an important role in the repair of genetic defects in germline cells.
Also Read: Meiosis II
Frequently Asked Questions
1. What is mitosis?
Mitosis is a form of nuclear division where the nuclei split into two, each identical to the original nucleus
2. What is Meiosis?
Meiosis is a type of nuclear division that results in four nuclei, each having ½ the chromosomes of the original cell
3. List out the difference between mitosis and meiosis
The difference between mitosis and meiosis are as follows:
- Mitosis was discovered by Walther Flamming, while meiosis was discovered by Oscar Hertwig.
- Karyokinesis occurs in mitosis during interphase while it occurs in meiosis during interphase 1
- Cytokinesis occurs only in telophase during mitosis while it occurs in Telophase 1 and telophase 2 during meiosis.
- The primary function of mitosis is general growth and repair. It is also used for cell reproduction. Meiosis, on the other hand, aims to provide genetic diversity through sexual reproduction.
- Asexual mode of reproduction is observed for mitosis. Sexual mode of reproduction is observed for meiosis.
4. State a few similarities between mitosis and meiosis.
The similarities between mitosis and meiosis are as follows:
- Mitosis and meiosis takes place in the cell nuclei
- Both involve cell division
- Both the processes occur in the M-phase of the cell cycle.
- In both cycles, the stages are common – metaphase, anaphase, telophase and prophase
- Synthesis of DNA occurs in both
- Cells of nervous tissue and the cardiac muscles tissue do not undergo the process of mitosis and meiosis once they are formed. In other words, they do not undergo division further.
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